A LOW-COST MULTICHIP PACKAGING TECHNOLOGY FOR MONOLITHIC MICROWAVE INTEGRATED-CIRCUITS

This paper describes a multichip module technology based on highly imp ermeable liquid crystal polymers (LCP's) to interconnect and package m onolithic microwave integrated circuits (MMIC's). Because of the low m oisture permeability of the LCP's, the packages can be made hermetic w ithout heavy expensive housings and can be two to four times lighter a nd one-fifth the cost of conventional ceramic based transmit/receive ( T/R) modules. The LCP material has a low dielectric constant (2.65) an d low-loss tangent and is manufacturable using high volume, large-area processing methods that provide very reliable highperformance circuit s at low cost. Using flip-chip bonded MMIC's attached to a high therma l conductivity, low coefficient of thermal expansion substrate, this i nnovative technology can meet a variety of commercial, military, and N ASA requirements.